I've experienced a weird crash when trying to find a QLineEdit in a QFormLayout.
Firstly, I created a QFormLayout and set a name for it:
QFormLayout *charColLayout = new QFormLayout; charColLayout->setObjectName("charColLayout");
Then, I created a QLineEdit, modified it a bit and add it in to the layout, and I also give it a name:
QLineEdit *delim = new QLineEdit;
delim->setMaxLength(1);
delim->setMaximumWidth(100);
delim->setText("/");
delim->setObjectName("delEdit");
charColLayout->addRow("Delimiter", delim);
Afterward, in a completely different function, I re-searched that layout with findChild():
QFormLayout *charcoal = secondHoriField->findChild<QFormLayout *>("charColLayout", Qt::FindChildrenRecursively);
It should be noted that secondHoriField is just a normal QLayout which my QFormLayout is located in.
Finally, I attempted to find that QLineEdit:
QLineEdit *delimEdit = charcoal->findChild<QLineEdit*>("delEdit", Qt::FindChildrenRecursively);
if (delimEdit == nullptr) {cerr << "error\n";} //debug
string curDelim = qStrToStr(delimEdit->text());
And it surprisingly came down with a crash, and as the output shown, it's because the delimEdit is null.
18:06:10: Starting D:\...\build-cryptog-Desktop_Qt_5_15_2_MinGW_64_bit-Debug\debug\cryptog.exe ...
error
18:06:17: The program has unexpectedly finished.
18:06:17: The process was ended forcefully.
18:06:17: D:\...\build-cryptog-Desktop_Qt_5_15_2_MinGW_64_bit-Debug\debug\cryptog.exe crashed.
But when I switched the findChild() function for this rather bruteforce-y line:
QLineEdit *delimEdit = dynamic_cast<QLineEdit*>(charcoal->itemAt(1)->widget());
cerr << qStrToStr(delimEdit->objectName()) << endl; //debug line
The program ran fine, and it showed the same name I set for the QLineEdit:
18:12:02: Starting D:\...\build-cryptog-Desktop_Qt_5_15_2_MinGW_64_bit-Debug\debug\cryptog.exe ...
delEdit
18:12:11: D:\...\build-cryptog-Desktop_Qt_5_15_2_MinGW_64_bit-Debug\debug\cryptog.exe exited with code 0
Why did this happened?
Another note: qStrToStr() is a function I implement to convert QString to std::string, and I have hand-checked it.
While findChild is a QObject method the itemAt is a QFormLayout method.
QObject::findChild
QFormLayout::itemAt
With addRow you add an item to the QFormLayout. This does not make it a child in the context of the QObject.
QFormLayout::addRow
The purpose of the QFormLayout is to organize the positioning of QWidgets, it is not meant to serve as a container. Maybe you could check whether the top level QWidget (e.g. QMainWindow) holding the QFormLayout would be a better choice as a parent for the QLineEdit.
Assuming you have some kind of QMainWindow:
QMainWindow myMainWindow;
// ...
QLineEdit *delim = new QLineEdit(&myMainWindow);
delim->setObjectName("delEdit");
//...
In another location:
auto delimEdit = myMainWindow.findChild<QLineEdit*>("delEdit");
I didn't find a proper solution to this problem, so I hope somebody can give me an answer to my problem:
I am using a normal QTreeWidget, but as items I use an own subclass of QTreeWidgetItem (because I needed to store some other information in the item). Now I want to use the itemClicked() signal by the QTreeWidget, but I think my slot doesn't get any signal and I think it has to do with the signature of itemClicked(), since it sends a QTreeWidgetItem and of course not my own subclass.
Is it possible that QTreeWidget doesn't detect a click on my own subclass items?
Here is my connection:
connect(treeWidget, SIGNAL(itemClicked(QTreeWidgetItem *)), this, SLOT(displayTransformData(QTreeWidgetItem*)));
And here is my slot:
void GUI::displayTransformData(QTreeWidgetItem* item) {
cout << "test" endl;
Q_actorTreeWidgetItem* actor_item = dynamic_cast<Q_actorTreeWidgetItem*>(item);
vtkSmartPointer<vtkActor> actor =
vtkSmartPointer<vtkActor>::New();
actor = actor_item->getActorReference();
double* position = new double[3];
position = actor->GetOrigin();
x_loc->setText(QString(std::to_string( position[0]).c_str() ));
}
I'm already trying to cast the item that I could get from the signal into my own subclass, but the slot function is never called, because the test from my cout line doesn't appear in the console.
I'm very grateful for every help!
The problem is your incorrect SIGNAL specification,
SIGNAL(itemClicked(QTreeWidgetItem *))
You should probably see a warning message at the console along the lines of:
QObject::connect: No such signal
tree_widget::itemClicked(QTreeWidgetItem *) in ...
From the documentation the actual signal spec is
void QTreeWidget::itemClicked(QTreeWidgetItem *item, int column)
So, using the old Qt4 syntax you need
connect(treeWidget, SIGNAL(itemClicked(QTreeWidgetItem *, int)),
this, SLOT(displayTransformData(QTreeWidgetItem*)));
If possible, however, you should make use of the newer Qt5 signal/slot syntax
connect(treeWidget, &QTreeWidget::itemClicked, this, &GUI::displayTransformData);
I've started to extend the qGet DownloadManager to emit the progress of a TransferItem, so that i can connect to it. I'm inserting the progress data into a cell of a TableView model for display with an Delegate, finally the delegate paints the progress bar. That works in theory, but i'm running into the following
Problem: when there are multiple downloads in parallel, then i get progress updates from both signals into both cells!
Both progress bars show progress data, but the signal is kind of mixed and not unique to the current index (QModelIndex index / index.row()).
(Please ignore the small transitioning problem between UserRoles (after clicking the download button "ActionCell" is displayed and then "Install", before the "ProgressBar" shows up.). That is not the main problem here. My question is about the index problem.) The text "112" and "113" is the int index.row.
Questions:
How to update a TableView with progress data for multiple ProgressBars?
What must i change to render a progress bar for each download?
Source
Emit progress of a download
I've added the following things to re-emit the signal through the classes, until it bubbles up to the top, where it becomes connectable from the GUI.
a connection from QNetworkReply - downloadProgress(qint64,qint64) to TransferItem - updateDownloadProgress(qint64,qint64)
void TransferItem::startRequest()
{
reply = nam.get(request);
connect(reply, SIGNAL(readyRead()), this, SLOT(readyRead()));
connect(reply, SIGNAL(downloadProgress(qint64,qint64)),
this, SLOT(updateDownloadProgress(qint64,qint64)));
connect(reply, SIGNAL(finished()), this, SLOT(finished()));
timer.start();
}
the SLOT function TransferItem - updateDownloadProgress(qint64,qint64) as receiver calculates the progress and stores it in progress (QMap<QString, QVariant>).
After the calculation the downloadProgress(this) signal is emitted.
// SLOT
void TransferItem::updateDownloadProgress(qint64 bytesReceived, qint64 bytesTotal)
{
progress["bytesReceived"] = QString::number(bytesReceived);
progress["bytesTotal"] = QString::number(bytesTotal);
progress["size"] = getSizeHumanReadable(outputFile->size());
progress["speed"] = QString::number((double)outputFile->size()/timer.elapsed(),'f',0).append(" KB/s");
progress["time"] = QString::number((double)timer.elapsed()/1000,'f',2).append("s");
progress["percentage"] = (bytesTotal > 0) ? QString::number(bytesReceived*100/bytesTotal).append("%") : "0 %";
emit downloadProgress(this);
}
QString TransferItem::getSizeHumanReadable(qint64 bytes)
{
float num = bytes; QStringList list;
list << "KB" << "MB" << "GB" << "TB";
QStringListIterator i(list); QString unit("bytes");
while(num >= 1024.0 && i.hasNext()) {
unit = i.next(); num /= 1024.0;
}
return QString::fromLatin1("%1 %2").arg(num, 3, 'f', 1).arg(unit);
}
When a new download is enqueued, i'm connecting the emitted downloadProgress(this) to the Slot DownloadManager - downloadProgress(TransferItem*). (dl is DownloadItem which extends TransferItem).
void DownloadManager::get(const QNetworkRequest &request)
{
DownloadItem *dl = new DownloadItem(request, nam);
transfers.append(dl);
FilesToDownloadCounter = transfers.count();
connect(dl, SIGNAL(downloadProgress(TransferItem*)),
SLOT(downloadProgress(TransferItem*)));
connect(dl, SIGNAL(downloadFinished(TransferItem*)),
SLOT(downloadFinished(TransferItem*)));
}
Finally, i'm re-emitting the download progress one more time:
void DownloadManager::downloadProgress(TransferItem *item)
{
emit signalProgress(item->progress);
}
Now the TableView with Delegate, doDownload(index) and ProgressBarUpdater
QTableView
with added QSortFilterProxyModel (for case-insensitivity)
with added ColumnDelegate, which renders DownloadButton and ProgressBar based on custom UserRoles. The delegate handles the button click: the SIGNAL downloadButtonClicked(index) is emited from the editorEvent(event, model, option, index) method.
actionDelegate = new Updater::ActionColumnItemDelegate;
ui->tableView->setItemDelegateForColumn(Columns::Action, actionDelegate);
connect(actionDelegate, SIGNAL(downloadButtonClicked(QModelIndex)), this, SLOT(doDownload(QModelIndex)));
The doDownload method receives the index and fetches the download URL from the model. Then the URL is added to the DownloadManager
and i'm setting up a ProgressBarUpdater object to set the progress data to the model at the given index. Finally i'm, connecting downloadManager::signalProgress to progressBar::updateProgress and invoke the downloadManager::checkForAllDone to start the download processing.
void UpdaterDialog::doDownload(const QModelIndex &index)
{
QUrl downloadURL = getDownloadUrl(index);
if (!validateURL(downloadURL)) return;
QNetworkRequest request(downloadURL);
downloadManager.get(request); // QueueMode is Parallel by default
ProgressBarUpdater *progressBar = new ProgressBarUpdater(this, index.row());
progressBar->setObjectName("ProgressBar_in_Row_" + QString::number(index.row()) );
connect(&downloadManager, SIGNAL(signalProgress(QMap<QString, QVariant>)),
progressBar, SLOT(updateProgress(QMap<QString, QVariant>)));
QMetaObject::invokeMethod(&downloadManager, "checkForAllDone", Qt::QueuedConnection);
}
The model update part: the ProgressBarUpdater takes the index and the progress and should update the model at the given index.
ProgressBarUpdater::ProgressBarUpdater(UpdaterDialog *parent, int currentIndexRow) :
QObject(parent), currentIndexRow(currentIndexRow)
{
model = parent->ui->tableView_1->model();
}
void ProgressBarUpdater::updateProgress(QMap<QString, QVariant> progress)
{
QModelIndex actionIndex = model->index(currentIndexRow, UpdaterDialog::Columns::Action);
// set progress to model
model->setData(actionIndex, progress, ActionColumnItemDelegate::DownloadProgressBarRole);
model->dataChanged(actionIndex, actionIndex);
}
The rendering part: i'm rendering the fake ProgressBar from the delegate; fetching the progress data with index.model()->data(index, DownloadProgressBarRole).
void ActionColumnItemDelegate::drawDownloadProgressBar(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
QStyleOptionProgressBarV2 opt;
opt.initFrom(bar);
opt.rect = option.rect;
opt.rect.adjust(3,3,-3,-3);
opt.textVisible = true;
opt.textAlignment = Qt::AlignCenter;
opt.state = QStyle::State_Enabled | QStyle::State_Active;
// get progress from model
QMap<QString, QVariant> progress =
index.model()->data(index, DownloadProgressBarRole).toMap();
QString text = QString::fromLatin1(" %1 %2 %3 %4 %5 ")
.arg(QString::number(index.row()))
.arg(progress["percentage"].toString())
.arg(progress["size"].toString())
.arg(progress["speed"].toString())
.arg(progress["time"].toString());
opt.minimum = 0;
opt.maximum = progress["bytesTotal"].toFloat();
opt.progress = progress["bytesReceived"].toFloat();
opt.text = text;
bar->style()->drawControl(QStyle::CE_ProgressBar,&opt,painter,bar);
}
I've added QString::number(index.row() to the progress bar text, so that each ProgressBar gets its row number rendered. In other words: the rendering is unique to the row, but the incoming progress data is somehow mixed.
I'm stuck on the index problem for a while now. Thank you in advance for your help.
Update: The issue is resolved!
Thank you very much ddriver!! I followed your suggestions and fixed it:
The DownloadManager tracks the progress for all transfers, and you keep each transfer item's data in the respective TransferItem.
The logical thing IMO would be to have a connection from each TransferItem to the corresponding ProgressBarUpdater, and emit from the transfer item.
However, in your case, you are reporting progress not from each individual transfer item, but from the download manager. So each time you are emitting a progress, you are emitting the progress for a particular transfer item to all progress bars.
connect(&downloadManager, SIGNAL(signalProgress(QMap<QString, QVariant>)),
progressBar, SLOT(updateProgress(QMap<QString, QVariant>)));
So instead of a
TransferItem --progress--> CorrespondingUI
you have a:
TransferItem --transferItem--> DownloadManager --progress--> AllUIs
This leads to having one single and varying progress for all progress bars, which corresponds to the last download that happen to report progress before the UI updated. Which is why you get no more variation after the first download is completed, as the manager only updates the progress for the second.
Finally, i'm re-emitting the download progress one more time:
void DownloadManager::downloadProgress(TransferItem *item)
{
emit signalProgress(item->progress);
}
And who exactly needs an anonymous progress, containing no information whatsoever to which transfer it applies? Aside from the bug of course.
Would you be so nice to explain, how to simplify it?
I was at the end of my mental rope yesterday when I commented, on a clear head it doesn't look all that overdone, but still I'd probably go for something more streamlined, involving 3 key components only:
DownloadsManager -> DownloadController -> UI
-> DownloadController -> UI
It just seems redundant to have a DownloadItem and then also a TransferItem, considering that a download is a transfer.
The model and view are totally unnecessary as well, as is storing the progress in the model rather than just having it as a member of the progress bar. You could go with just a regular widget for each download, and place them in a vertical layout.
Update:
The excessive, unnecessary compartmentalization has led to a level of fragmentation which makes it hard to get to the data, needed to make it work once you put everything together. The main issue is you have no way to tie a transfer item to the right progress bar updater, and since you still haven't posted all of the relevant code, the simplest possible solution I can offer involves the following minor changes:
// in DownloadManager
void signalProgress(QMap<QString, QVariant>); // this signal is unnecessary, remove
void DownloadManager::downloadProgress(TransferItem *item) // change this
{
registry[item->request.url()]->updateProgress(item->progress);
}
QMap<QUrl, ProgressBarUpdater *> registry; // add this
// in UpdaterDialog
void UpdaterDialog::doDownload(const QModelIndex &index)
{
QUrl downloadURL = getDownloadUrl(index);
if (!validateURL(downloadURL)) return;
QNetworkRequest request(downloadURL);
downloadManager.get(request); // QueueMode is Parallel by default
ProgressBarUpdater *progressBar = new ProgressBarUpdater(this, index.row());
progressBar->setObjectName("ProgressBar_in_Row_" + QString::number(index.row()) );
// remove the connection - source of the bug, instead register the updater
downloadManager.registry[downloadURL] = progressBar;
QMetaObject::invokeMethod(&downloadManager, "checkForAllDone", Qt::QueuedConnection);
}
That's pretty much it, the progress updater is associated with the URL, and in DownloadManager::downloadProgress instead of emitting the progress to all progress updaters, you simply lookup the one which actually corresponds to the particular download, and only update its progress. It is somewhat clumsy, but as I said, if your design is proper, it would not be needed and you wouldn't have the problem in the first place.
There are other solutions as well:
change the DownloadManager's signal to void signalProgress(TransferItem *), and the body of downloadProgress toemit signalProgress(item); , change to void ProgressBarUpdater::updateProgress(TransferItem *), and in the body compare the transfer item's request's url to the one in the model at the currentIndexRow, and only model-setData() if it is the same. This solution is not very efficient, since it will emit to all progress updaters just to modify one.
cut out the middleman, what I've been suggesting from the start, make DownloadManager ::get() return a pointer to the DownloadItem/TransferItem created in its body, then in UpdaterDialog::doDownload() you can connect the transfer item directly to the appropriate progress updater, so you will no longer need DownloadManager::downloadProgress() and the signalProgress signal, you only need to change the signature of the signal in TransferItem to void downloadProgress(QMap<QString, QVariant>); and emit the progress rather than the item. This is actually the most efficient solution, as it involves nothing extra, jsut the removal of unnecessary stuff.
I have a UIForm named "Spell" that contains inter alia QGridLayout with custom widgets named "PElement". The amount of PElement widgets depends on number of spells in my database. So, I fill QGridLayout by ui->spellLayout->addWidget(...)
When PElement is clicked it emits signal. I need to connect each of PElement in QGridLayout with slot in Spell class. I have no idea how to do it.
Thanks for help!
#edit
this is a function that add PictureElement to QGridLayout
void Spells::setSpellList(QString lore)
{
QList<QStringList> elementList = Database::instance()->getSpellElement(lore);
while(ui->spellLayout->count() > 0) {
QWidget *w = ui->spellLayout->itemAt(0)->widget();
ui->spellLayout->removeWidget(w);
delete w;
}
int w,h;
w = 162;
h = 203;
int maxCol = ui->spellScrollArea->width() / (w + ui->spellLayout->spacing());
if(maxCol<=0) {
Indicator::instance()->hide();
return;
}
foreach(QStringList list, elementList){
PictureElement *spellElement = new PictureElement;
spellElement->setText(list.at(0));
spellElement->setPixmap(list.at(1));
spellElement->setMinimumSize(w, h);
ui->spellLayout->addWidget(spellElement,
ui->spellLayout->count() / maxCol,
ui->spellLayout->count() % maxCol);
spellElement->show();
}
Indicator::instance()->hide();
}
What I want:
connect every PictureElement (SIGNAL clicked) from QGridLayout with slot in Spells class.
I am not quite sure where the issue ist. Assuming your class PictureElement inherits QObject, contains the Q_OBJECT macro and emits the signal, your simply add a connect line in your foreach loop:
foreach(QStringList list, elementList){
PictureElement *spellElement = new PictureElement;
...
QObject::connect(spellElement, SIGNAL(clicked()), this, SLOT(slotname()));
}
You are already in the Spells class so theaccess shouldn't be an issue. Of course the slotname() function needs to be defined as a slot in the header. To identify which PictureElement emitted the signal within the slot you can use the QObject::sender() method.
I used Qt Creator to make a "keyboard" window with sixty QPushButtons and one QLineEdit. How can I make the buttons to add characters into QLineEdit text box? If I press a QPushButton with the label 'Q' on it, I want the program to add the Unicode character 'Q' on the text box.
One way to do this would be to just connect the 'clicked' signal from all the buttons to a slot, and then handle the adding of the character there.
For example, if the all keyboard buttons are inside a layout called 'buttonLayout', in your MainWindow constructor you can do this:
for (int i = 0; i < ui->buttonLayout->count(); ++i)
{
QWidget* widget = ui->buttonLayout->itemAt( i )->widget();
QPushButton* button = qobject_cast<QPushButton*>( widget );
if ( button )
{
connect( button, SIGNAL(clicked()), this, SLOT(keyboardButtonPressed()) );
}
}
Then in the slot implementation, you can use QObject::sender(), which returns the object that sent the signal:
void MainWindow::keyboardButtonPressed()
{
QPushButton* button = qobject_cast<QPushButton*>( sender() );
if ( button )
{
ui->lineEdit->insert( button->text() );
}
}
OPTION 1 - Multiple signals and slots
Connect all pushbuttons clicked() signal to a slot
// Let button01 be the A
connect(ui->button01, SIGNAL(clicked()), this, SLOT(buttonClicked()));
...
// Let button 60 be the Q
connect(ui->button60, SIGNAL(clicked()), this, SLOT(buttonClicked()));
In the buttonClicked() slot you have to figure out which button was clicked and append the corresponding letter to the line edit.
void buttonClicked()
{
QObject* callingButton = QObject::sender();
if (callingButton == button01)
ui->lineEdit->setText(ui->lineEdit->text()+ "A");
...
else if (callingButton == button60)
ui->lineEdit->setText(ui->lineEdit->text()+ "Q");
}
OPTION 2 - Subclass QPushButton
You could subclass QPushButton in order to avoid the multiple ifs. In your subclass just catch the mouse release event and emit a new signal which will contain the button's text
void KeyboardButton::mouseReleaseEvent(QMouseEvent* event)
{
emit clicked(buttonLetter); // Where button letter a variable of every item of your subclass
}
Similarly connect the clicked(QString) signal with a slot
connect(ui->button01, SIGNAL(clicked(QString)), this, SLOT(buttonClicked(QString)));
...
connect(ui->button60, SIGNAL(clicked(QString)), this, SLOT(buttonClicked(QString)));
void buttonClicked(QString t)
{
ui->lineEdit->setText(ui->lineEdit->text()+ t);
}
I have created an application with a similar issue, trying to convert the qpushbutton text to the qlineedit itself. The key is how you initialize the buttons and to use polymorphism in your function. To create an emit signal wont work for individual characters. The .digitValue will work if the case if for numerics (which the buttons would be of type int), but qt doesnt have a character value (I should say after 6hrs of reading qt doc and another 4 of trying different combinations it would not work), I think it has to do with how many bits it takes to store each variable type in an array. I even tried converting the button->text to QString to use with the emit function as a signal prototyped.
I do not know what your button layout is, but I will give you a synopsis of what I did. I first created a global, static const char array containing all the letters needed e.g.
static const char vowelarray[] = "AEIOU";
Then initialized the QPushButtons with in the MainWindow function, using iteration, setting a for loop's terminating condition equal to the size char array (in your case 60?). This all depends on your button layout though. I personally created a void function (setLocation) for the button->setGeometry of each button and iterated the setGeometry, and then passed the function to the MainWindow Function, at end of fucntion. The following code was used to initialize the buttons, connect signals to slots, and use polymorphism to connect to lineedit.
for (int i = 0; i < 26; i++){
characterButton[i] = new QPushButton(chararry[i], this); `
characterButton[i] -> setStyleSheet("QPushButton{background: grey; color: brown}");
connect(characterButton[i],SIGNAL(released(),this,SLOT(characterPushed()));
}
setLocation();
Then created a void function (e.g. void MainWindow::characterPuched()) where the following code was used:
void MainWindow::characterPushed(){
QPushButton *characterButton = (QPushButton*) sender();
if (characterButton )
{
lineEdit -> setText(letters.insert(letters.size(), characterButton -> text()));
}
lineEdit -> setText(letters);
}
of course letters was a global variable as well as:
QString letters = "";
and of course the QPushButtons and the function were prototype in the header file as a private variables and slots, e.g.
private:
QPushButton *characterButton[26];
the variable 'letters' was used to extract and input text to and from the line edit for further functions throughout the application.
Best Luck!!``